Centrifugal fan and impeller thereof

ABSTRACT

An impeller applied to a centrifugal fan includes a base plate, a hub and a plurality of blades. The hub is connected to the base plate. The blades are disposed around the base plate and around the hub. The blades are the backward leaning structures and each blade has at least one inversely inflective portion located at its tail. A centrifugal fan including the impeller is also disclosed.

BACKGROUND OF THE INVENTION

1. Field of Invention

The invention relates to a fan and, in particular, to a centrifugal fan.

2. Related Art

Since the present electronic products are rapidly developed towards the goals of high performance, high frequency, high speed and compactness, the generated heat of the electronic products becomes greater. However, the electronic products may be unstable in the high temperature, which results in the poor reliability thereof. Thus, the heat dissipation has become an important issue of the present electronic products.

The fan is commonly used as a heat dissipating device for the electronic product. FIG. 1 a and FIG. 1 b are top views of two kinds of conventional centrifugal fans 1 and 1′, both of which have a plurality of blades. Based on the arrangement, the blades may be forward leaning blades 11 (shown in FIG. 1 a) or backward leaning blades 11′ (shown in FIG. 1 b). The rotation directions of the blades are shown by the arrows in FIGS. 1 a and 1 b. Under the same rotation speed, the forward leaning blades 11 can output higher air pressure for providing better heat dissipation effect. However, the loading of the motor increases, and the power consumption is higher. Contrariwise, the backward leaning blades 11′ provide a heat dissipation effect not as good as that provided by the forward leaning blades 11, but the power consumption of the backward leaning blades 11′ is lower. Therefore, the manufacturer can choose different types of the blades according to the actual needs of power consumption.

As shown in FIG. 2, a conventional centrifugal fan 2 includes an impeller 21 and a motor 22. The impeller 21 includes a base plate 213, a hub 211, and a plurality of backward leaning blades 212. The base plate 211 is connected to the hub 211, and the blades 212 are disposed on the base plate 211 and around the hub 211. The impeller 21 further includes a connecting ring 214, which is connected to a side of the blades 212 opposite to another side thereof facing the base plate 213. The motor 22 is accommodated in the hub 211 for driving the impeller 21 to rotate.

When the impeller, 21 rotates, airflow enters. the center of the impeller 21. Then, the blades 212 force the airflow to radiately flow out of the blades 212. Since the air pressure provided by the backward leaning blades is smaller than that of the forward leaning blades, the fan 2 utilizing the backward leaning blades provides inferior heat dissipation effect.

It is therefore an important subject of the invention to improve the heat dissipation efficiency of the backward leaning blades with lower power consumption.

SUMMARY OF THE INVENTION

In view of the foregoing, the invention is to provide a centrifugal fan and an impeller thereof that can improve the efficiency thereof for enhancing the heat dissipation effect with lower power consumption.

To achieve the above, an impeller of the invention includes a base plate, a hub, and a plurality of blades. The hub is connected to the base plate. The blades are disposed on the base plate and around the hub. In the invention, the blades are backward leaning structures and each blade has at least one inversely inflective portion located at a tail of the blade.

To achieve the above, a centrifugal fan of the invention includes an impeller and a motor accommodated underneath the impeller. The impeller includes a base plate, a hub, and a plurality of blades. The hub is connected to the base plate. The blades are disposed on the base plate and around the hub. In the invention, the blades are backward leaning structures and each blade has at least one inversely inflective portion located at a tail of the blade.

As mentioned above, the centrifugal fan and impeller of the invention have the blades of the backward leaning structures, each of which has at least one inversely inflective portion located at a tail of the blade. Thus, when the airflow flows through the tails of the blades, the inversely inflective portion is capable of increasing the airflow quantity of the fan. As a result, the efficiency of the fan can be efficiently improved for enhancing the heat dissipation effect with lower power consumption.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become more fully understood from the detailed description given herein below illustration only, and thus is not limitative of the present invention, and wherein:

FIG. 1 a is a top view of a conventional centrifugal fan that has forward leaning blades;

FIG. 1 b is a top view of a conventional centrifugal fan that has backward leaning blades;

FIG. 2 is a schematic view of a conventional centrifugal fan;

FIG. 3 a is a top view of a centrifugal fan and an impeller thereof according to a preferred embodiment of the invention;

FIG. 3 b is an enlarged diagram showing an inversely inflective portion shown in FIG. 3 a;

FIG. 4 is a three dimensional view of the centrifugal fan according to the preferred embodiment of the invention; and

FIG. 5 is a schematic diagram showing efficiency curves of the conventional centrifugal fan and the centrifugal fan of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements.

FIG. 3 a is a top view of a centrifugal fan and an impeller thereof according to a preferred embodiment of the invention, and FIG. 4 is a three dimensional view of the centrifugal fan and the impeller. The centrifugal fan 3 includes an impeller 31 and a motor 32. The impeller 31 includes a base plate 312, a hub 311, and a plurality of blades 313. The motor 32 is accommodated in the hub 311 for coupling to the impeller 31 and driving it to rotate. The hub 311 is connected to the base plate 312. The blades 313 are disposed on the base plate 312 and around the hub 311. In the embodiment, the base plate 312 is ring-shaped, and the base plate 312, the hub 311 and the blades 313 are integrally formed as a single unit. The blades 313 are backward leaning structures, and each blade 313 has an inversely inflective portion 3131 located at a tail of the blade 313. FIG. 3 b is an enlarged diagram showing the inversely inflective portion 3131. The inversely inflective portion 3131 has a smooth surface and is used to increase the airflow quantity and efficiency of the impeller 31. In practice, the present invention may provide several inversely inflective portions at the tail of each blade according to the actual needs.

The impeller 31 further includes a connecting ring 314, which is connected to a side of the blades 313 opposite to another side thereof facing the base plate 312. Similarly, the connecting ring 314 and the blades 313 may be integrally formed.

With reference to FIG. 5, an experimental analysis is obtained by comparing the conventional centrifugal fan and the centrifugal fan of the present invention. Herein, the X axis represents the airflow quantity, and the Y axis represents the air pressure. Under the same rotation speed of 4060 RPM, the centrifugal fan of the invention can provide better efficiency than the conventional one according to the efficiency curve of the experimental analysis.

In summary, the centrifugal fan and impeller of the invention have the blades of the backward leaning structures, each of which has at least one inversely inflective portion located at a tail of the blade. Thus, when the airflow flows through the tails of the blades, the inversely inflective portion is capable of increasing the airflow quantity of the fan. As a result, the efficiency of the fan can be efficiently improved for enhancing the heat dissipation effect with lower power consumption.

Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments, will be apparent to persons skilled in the art. It is, therefore, contemplated that the appended claims will cover all modifications that fall within the true scope of the invention. 

1. An impeller comprising: a base plate; a hub connected to the base plate; and a plurality of blades disposed on the base plate and around the hub, wherein each of the blades has at least one inversely inflective portion located at a tail of the blade.
 2. The impeller of claim 1, wherein the base plate, the hub and the blades are integrally formed as a single unit.
 3. The impeller of claim 1, wherein the inversely inflective portion has a smooth surface.
 4. The impeller of claim 1, wherein the base plate is ring-shaped.
 5. The impeller of claim 1, further comprising: a connecting ring connected to a side of the blades opposite to another side of the blades facing the base plate.
 6. The impeller of claim 5, wherein the connecting ring and the blades are integrally formed.
 7. The impeller of claim 1, wherein the blades are backward leaning structures or curved structures.
 8. A centrifugal fan comprising: an impeller comprising a base plate, a hub, and a plurality of blades, wherein the hub is connected to the base plate, and the blades are disposed on the base plate and around the hub; and a motor coupled to the impeller for driving the impeller to rotate, wherein each of the blades has at least one inversely inflective portion located at a tail of the blade.
 9. The centrifugal fan of claim 8, wherein the base plate, the hub and the blades are integrally formed as a single unit.
 10. The centrifugal fan of claim 8, wherein the inversely inflective portion has a smooth surface.
 11. The centrifugal fan of claim 8, wherein the base plate is ring-shaped.
 12. The centrifugal fan of claim 8, wherein the motor is accommodated in the hub.
 13. The centrifugal fan of claim 8, further comprising: a connecting ring connected to a side of the blades opposite to another side of the blades facing the base plate.
 14. The centrifugal fan of claim 13, wherein the connecting ring and the blades are integrally formed.
 15. The centrifugal fan of claim 8, wherein the blades are backward leaning structures or curved structures. 